Plastic Intake Manifold May Crack Causing Coolant Leak on Mercury Mountaineer

The composite (plastic) intake manifold may crack near the thermostat housing and cause a coolant leak. Ford released an updated manifold that was reinforced to prevent a recurrence. No recall was issued for this problem but Ford did extend the warranty to seven years on some models from the date of purchase.

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Average mileage: 127,074 (16,700–209,000)
Electrical & Lights affected: 4.6L V8
7 model years affected: 1998, 1999, 2002, 2003, more2004, 2005, 2006
62 people reported this problem
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Viewing 1 - 20 of 42 problem details
1999 Mercury Mountaineer 76,220 mi,
Driving down the road, pressed gas pedal and white smoke started coming out back. I pulled over and antifreeze was all over the inside of the engine and hood. Looked and intake manifold where thermostat is housed was completely cracked. It's been leaking for the past month causing antifreeze to cause the ignition coils in cylinder 7 and 8 to go bad. Now it's completely cracked. A shame ford never officially recalled this, poor design that is now costing consumers a hefty bill for a new intake manifold to replace something that wasn't manufactured right to begin with!
2004 Mercury Mountaineer 100,058 mi,
I just purchased this vehicle from a private seller. I saw that it was leaking coolant but got a good price on the mountaineer so purchased it anyway. I took it in to get inspected and had every problem listed on this forum. intake manifold was cracked could not find anywhere but dealer cost 700.00 with labor. It also needed rear bearings and hubs replaced and the back emblem has a crack around it. Total cost to repair all problems 1400.00. That bill should go directly to ford because this is a problem that seems to occur on many of the mountaineers.
2005 Mercury Mountaineer 108,000 mi,
coolant leak at the thermostat. Replaced intake manifold. $850 incl labor. Shame on Ford. This has been a recurring problem since 1997 at least. Eight years of cracking intake manifolds? Quality is job ZERO.
2003 Mercury Mountaineer 160,000 mi,
needs new Intake Manifold gasket. $400 part plus labor. my as well get new thermostat too. $975.
not fixed yet cause i cant afford to at this time
2005 Mercury Mountaineer 160,000 mi,
Plastic intake is leaking
2002 Mercury Mountaineer 120,000 mi,
heater stopped working and brought attention to low coolant. car was also skipping occasionally. when I inspected engine after adding coolant and getting home I found coolant around spark plug. cause of skip. how did the coolant get there? upon further inspection it looked like it was coming from around thermostat. I thought a gasket maybe. After removing intake manifold I found the problem was not the gasket but a plastic intake that had broken around thermostat. Expensive and time consuming repair. also replaced plugs and the coil pack on the cylinder where the coolant was leaking. continues to run fine now.
2002 Mercury Mountaineer 148,000 mi,
I'm purchasing a 2002 mercury mountaineer from a in house financing car dealership and after I drove it for bout a week I noticed the truck started running hot and I finally took it to the shop and they told me that the intake manifold is falling apart because its plastic and its getting to hot and they wanted to charge me around 700 dollars to get it fixed
2002 Mercury Mountaineer 189,000 mi,
This problem will cause water to leak into the cylinders and cause them to miss fire making you think there is a problem with the plugs and coils. The car will run horribly but if you look closer you will find that it is in dead the plastic piece under the thermostat housing. It is a real pain. I am still trying to get his fixed and I am sure it is going to cost me a lot of money because it is no longer under warranty.
2005 Mercury Mountaineer 145,000 mi,
Air con problems took to dealer had a crack after $1600.00 now it's works fine and i wasn't told this was a common problem. I had taken my vehicle once before while vehicle was still under warranty and i was told all was repaired even though it wasn't.
2003 Mercury Mountaineer 144,677 mi,
heater wasn't working. it's at garage right now and they said the manifold is cracked and need to get part from the Ford dealer. Part alone is $441. Going to cost over $800 for total repair. HAVE to get it fixed because it's leaking antifreeze all over inside. This vehicle has cost me thousands since i drove it off the lot brand new. Sooooo frustrated right now. It also needs new brakes and hub bearings, again. Plus i just put 4 new tires on it last month. It's worse than a new car payment.
2002 Mercury Mountaineer 146,000 mi,
cracked manifold thermostat housing. Tried to stop the leak with liquid weld--no good. As soon as the car heats up it breaks the welding.
1999 Mercury Mountaineer 17,400 mi,
antifreeze is leaking down on the oil pan [passenger side] cant find where its coming from
2006 Mercury Mountaineer 125,000 mi,
Please tell me who ever thought using PLASTIC in radiators and cooling system was a good idea. Our Mountaineer thermostat housing cracked AFTER replacing the radiator, it still wasn't fixed. Plastic in an engine .. dear lord
1998 Mercury Mountaineer 100,110 mi,
Starting leaking antifreeze, was told there was a crack on the radiator no need to change yet.. That this problem was common on this model vehicle, now 5months later it started overheating & smoking. Was told by Mechanic, radiator has completely crack special with these below zero temperatures. Now It needs to be replace causing me more than $400 in parts & Labor. These seems to be a on going issue with these make & model vehicle. With so many complains WHY hasn't it been recalled???
1998 Mercury Mountaineer 133,000 mi,
Leaking coolant below thermostat
2003 Mercury Mountaineer 180,000 mi,
Have engine miss that was diagnosed as oil and water in the spark plug recesses of the two rear cylinders. Service shop blew the liquid out of the recess of the two contaminated plug recesses and enging ran smoothly for a few weeks. I noticed that the coolant overflow tank was low and brought the coolant up to the "cold mark". The next time I ran the vehicle, the miss fire had returned. I checked the coolant level and the overflow tank was empty. I then pulled the coil/boots for the entire engine and there was antifreeze residue in 3 or the 4 spark plug recepticles on the left bank. I then found some corrosion at the base of the thermostat housing and so I drained the radiator and then removed the thermostat. At the bottom of the housing I could see about a 1 inch section of the seal sticking out. The manifold had broken at that location.
I replaced water pump, oil change, n a new battery because it was over heating, a month later now its white snoke coming from the back,n now the engine is rocking, sound like something stuck, i think its crazy that they wont recall that, in it can catch on fire, like come on now!!!
2002 Mercury Mountaineer 174,955 mi,
One morning I was warming up my 2002 Mercury Mountaineer and noticed a funny smell and a stream of water leaving my drive-way. The temperature gradually began to elevate the typical half marker. I haven't move or driven the truck since. I enjoy the comfort a drivability of this vehicle but over all since I've been in ownership there have been several issues. Ex; Gas needle non-operable, no day time running lights, fog light shortage, door-open alert and interior light, lack of radio volume control, ball joint and rotor issues(right wheel shakes during breaking),Transmission slip due to leak,(trans. pan seal, trans. pan strainer).
2003 Mercury Mountaineer 145,000 mi,
Less than 30 days of buying vehicle. Lost heat. Loosing coolant. Local mechanic ran a pressure test. And $700.00 later it was fixed. Have had nothing but problems since.